[virt-viewer PATCH v4 1/1] remote-viewer: add handler for SIGINT signal

[Daniel P. Berrangé]

On Fri, Jan 17, 2020 at 04:06:13PM +0100, Francesco Giudici wrote:
> When remote-viewer is started from terminal, CTRL-C sends a SIGINT
> signal to the program causing immediate termination. On linux clients
> usb redirected devices are left without any kernel driver attached,
> causing them to appear as no more available to the host.
> Add a SIGINT handler to allow a clean exit, in particular to allow
> the kernel to attach back the host driver.
> The issue is present on linux only.
> 
> To perform usb device redirection, virt-viewer leverages spice-gtk
> library, which in turn relies on usbredir library, which uses libusb.
> In order to take control of the usb device the auto-loaded kernel
> driver must be detached. This is achieved (in the very end) with
> libusb_detach_kernel_driver(). Then the device interfaces can be claimed
> with libusb_claim_interface() and get in control to the application.
> During normal application termination, the usb channel is teared down,
> performing a reset of the usb device and giving back the control of the
> device to the kernel (libusb_attach_kernel_driver()).
> If the application quits without doing this, the device interfaces will
> end up with no driver attached, making them not usable in the host
> system.
> 
> Note that enabling libusb_set_auto_detach_kernel_driver() does not solve
> the issue, as this is just a convenient API from libusb: libusb will
> take care of detaching/attaching the driver to the interfaces of the usb
> device each time a call to libusb_release_interface() and
> libusb_claim_interface() is performed. An unexpected quit of the
> application will skip the libusb_release_interface() call too, leaving
> the interfaces without any driver attached.
> 
> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1713311
> 
> Signed-off-by: Francesco Giudici <fgiudici at redhat.com>
> ---
>  src/virt-viewer-app.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)

Thanks, this is merged

Regards,
Daniel
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